1. Field of the Invention
The present invention relates to a packaging apparatus in which a produce is sealed within a container. More particularly to a process which evacuates, flushes and seals the container within a controlled environment.
2. Description of the Prior Art
It is well known that the quality of most products, particularly foods, can be best maintained during storage if they are placed in a sealed container in which the amount of oxygen has been significantly reduced. In foods the presence of oxygen within the container stimulates the growth of bacteria and molds, causing loss of flavor and eventually spoilage. The less oxygen remaining within a sealed package the greater the efficiency of the packaging apparatus and the longer the product will last during storage.
Various types of packaging machines have been developed to reduce the amount of oxygen remaining within a sealed package. For example, U.S. Pat. No. 4,409,252, issued to Buschkens et al., discloses a number of work stations at which a tack seal attaches a lid to a container, gas is blown between the lid and the container and then the container is sealed at the final station. There is no means for preventing entrance of oxygen or other contaminants during the container's transfer to the sealing station or during the final sealing process.
U.S. Pat. No. 4,624,099, issued to Harder, discloses an apparatus that evacuates air simultaneously from above and below the product container, the container is filled with an inert gas and then the container is removed from the chamber and the container is sealed. The sealing of the container occurs at a station separate from the back filling process, allowing contaminants to enter between stations.
U.S. Pat. No. 4,294,859, issued to Lundquist et al., discloses an apparatus having a first chamber into which the product and container are sealed, the air is evacuated from the chamber, the lid is partially sealed, and then the chamber is flushed with an inert gas. The food unit is then removed from the chamber and the container is flushed a second time outside the chamber. The food unit is then moved into a second chamber, the chamber is evacuated, and the lid to the container is sealed. Alternatively, the food unit may be filled with a gas prior to sealing. In this invention the flushing occurs separately from the final vacuum and final seal, losing the benefits of the flushing by allowing contaminants to enter the food units before they enter the final chamber.
U.S. Pat. No. 3,668,820, issued to Parvin et al., discloses an apparatus in which a lid is tack sealed to a food unit, the unit is then placed within a chamber, the chamber is evacuated, and the unit is sealed. The patent does not disclose any means for flushing with an inert gas.
U.S. Pat. No. 3,508,373, issued to Robinson, discloses simultaneous evacuation and flushing of a food unit; however, the sealing process is accomplished at a separate station, permitting contaminants to enter the food unit during the transfer from one station to another.